Synthesis of Single‐Phase β‐Yb 2 Si 2 O 7 and Properties of Its Sintered Bulk

Single‐phase β‐Yb 2 Si 2 O 7 was synthesized by solid‐state reaction using Yb 2 O 3 and SiO 2 gel. SiO 2 gel significantly decreased the synthesis temperature and shortened the holding time. Bulk Yb 2 Si 2 O 7 was obtained by pressureless sintering. Grain size, relative density (92.9%), and flexural strength [(182.3 ± 2.0) MP a] were enhanced as the sintering temperature increased and equiaxed grains were obtained with an average grain size of approximately 3 μm. Bulk Yb 2 Si 2 O 7 possessed a suitable thermal expansion coefficient [(4.64 ± 0.01) × 10 −6 /K] between 473 and 1573 K, and the thermal conductivities at 300 and 1400 K were 4.31 and 2.27 W/m·K, respectively.